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为探讨金属磁记忆无损检测技术预测再制造毛坯的剩余寿命,采用金属磁记忆技术检测了拉-拉疲劳过程中45钢光滑试件和预制缺陷试件表面的磁记忆信号变化规律。结果表明:45钢光滑试件疲劳试验过程中,在试件断裂之前,随疲劳载荷作用循环次数的增加,试件表面磁信号的分布规律变化不大,试件断裂后断口处磁信号发生激变;表面预制槽型缺陷的45钢试件在疲劳试验过程中,其表面磁信号在预制缺陷扩展后发生变化,且缺陷部位磁信号峰峰值随裂纹长度增加而持续增大。研究分析认为,金属磁记忆检测技术对疲劳裂纹的扩展情况有较好的反映,有望通过建立磁记忆信号峰峰值——疲劳裂纹长度a的关系模型,实现金属磁记忆技术对再制造毛坯剩余寿命的定量方法。但是,采用金属磁记忆技术预测疲劳裂纹萌生前铁磁材料的损伤程度尚需进一步探索。 相似文献
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金属磁记忆检测技术用于再制造毛坯寿命预测的试验研究 总被引:4,自引:0,他引:4
为探讨金属磁记忆无损检测技术预测再制造毛坯的剩余寿命,采用金属磁记忆技术检测了拉-拉疲劳过程中45钢光滑试件和预制缺陷试件表面的磁记忆信号变化规律.结果表明45钢光滑试件疲劳试验过程中,在试件断裂之前,随疲劳载荷作用循环次数的增加,试件表面磁信号的分布规律变化不大,试件断裂后断口处磁信号发生激变;表面预制槽型缺陷的45钢试件在疲劳试验过程中,其表面磁信号在预制缺陷扩展后发生变化,且缺陷部位磁信号峰峰值随裂纹长度增加而持续增大.研究分析认为,金属磁记忆检测技术对疲劳裂纹的扩展情况有较好的反映,有望通过建立磁记忆信号峰峰值--疲劳裂纹长度a的关系模型,实现金属磁记忆技术对再制造毛坯剩余寿命的定量方法.但是,采用金属磁记忆技术预测疲劳裂纹萌生前铁磁材料的损伤程度尚需进一步探索. 相似文献
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利用电子拉伸试验设备和弱磁场测量系统,对受静拉伸载荷的试样表面漏磁场进行测量,研究了试件在弹性阶段、均匀变形阶段和非均匀变形阶段磁记忆信号随载荷大小不同的变化规律;最后,根据试验现象,结合晶粒滑移理论基础对静载荷下磁记忆检测的机理作了解释。试验和理论研究的结果表明:采用磁记忆方法对承载疲劳载荷铁磁构件由应力集中造成的早期损伤进行检测是可行的。 相似文献
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Metal magnetic memory technique has provided a new arena for assessing stress status, especially for detecting early damage in ferromagnetic materials. To investigate the magnetomechanical effect of metal magnetic memory phenomenon, the rotary bending fatigue experiments under different stress levels were conducted. The normal components of magnetic field intensities induced by cyclic bending stresses on the surfaces of 45-steel specimens were measured throughout the fatigue process. The results show that surface magnetic fields generated contains reversible and irreversible process prior to failure, while there is a substantial increase just before fracture. Possible reasons for the variations of magnetic fields and corresponding signal characteristics to identify damage zones were discussed. 相似文献
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磁测应力是近几年发展起来的最新无损检测技术,分为金属磁记忆检测技术和基于逆磁致伸缩效应的磁各向异性检测技术。该技术适用于铁磁性金属构件失效的早期诊断,特别是在铁磁构件的疲劳强度和寿命评估研究中更具广阔的发展空间。介绍了磁测应力技术的基本概念、特点及国内外的研究现状,分析了目前存在的问题及其发展趋势。 相似文献
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为对旋转弯曲疲劳过程中的磁记忆信号进行分析,从磁记忆的物理基础出发,把旋转弯曲疲劳试验件看成一个磁体,试件的疲劳破坏过程就是试件由一个磁体变成两个磁体的过程。指出在试件表面检测到的磁场是环境磁场、试件的磁感应磁场和漏磁场的叠加,并分析了沿试件轴向的法向磁信号的分布变化。最后通过旋转弯曲疲劳试验,验证了理论分析结果。理论分析和试验结果均显示,疲劳破坏前法向磁信号出现显著的异常特征,可用其进行疲劳损伤诊断。 相似文献
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Magnetic memory testing (MMT) method is a novel non-destructive testing technique due to its unique advantages of stress concentration identification and early damage detection for ferromagnetic materials. However, a thorough understanding of the impact of exciting magnetic source and cyclic stress on the residual magnetic field variation has not been clearly addressed. The surface magnetic memory signal Hp(y) induced by applied magnetic field and cyclic tensile stress was measured throughout the fatigue process. The correlation of Hp(y) and its gradient K changes with loading cycles and applied magnetic field intensity H reported. The results show that applied magnetic field can only change the magnitude of MMT signal instead of changing the Hp(y) curve׳s profile. The Hp(y) value increases with the increase of the H, and the K value is approximately linear to the H. The maximum gradient Kmax indicating the degree of stress concentration increases with the increase of either stress cycles or H. The phenomenon was also discussed from the view of the magnetic dipole in a ferromagnet. 相似文献
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Variation of stress-induced magnetic signals during tensile testing of ferromagnetic steels 总被引:1,自引:0,他引:1
Stress alone applied to ferromagnetic materials can induce the generation of weak magnetic signals on their surfaces, which can be potentially used to estimate the degree of damage of ferromagnetic components. In this paper, the normal component of stress-induced magnetic field, Hp(y), was measured during tensile tests on the surfaces of sheet specimens of three ferromagnetic materials. It has been concluded that Hp(y) depends on the applied stress and will present different characteristics on the elastic and plastic deformation stages, respectively. The phenomenon of sharp changes in magnetic signals occurring at the instant of fracture was also discussed from the view of the interaction energy in a ferromagnet. 相似文献
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Zbigniew H. urek 《NDT & E International》2006,39(8):675-679
Materials diagnostic by NDT is an important element of manufacture and service. The classic methods of technical diagnostic do not provide extensive knowledge of the technical condition of all of the elements. Constructional elements built of iron alloy can be characterised by magnetic properties, hence it may be inspected by magnetic methods and the recognition of material technical condition becomes more comprehensive. The paper presents the influence of fatigue processes on the magnetic parameters of the material. The results of the monitoring procedures of the wheel set tread surface in practise are also given. 相似文献
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漏磁通检测中铁磁材料的磁化状态 总被引:3,自引:3,他引:0
讨论缺陷引起的附加磁场和外磁化场对铁磁材料的磁化作用,引入有效磁导率和平衡磁导率来描述铁磁材料不同区域的磁化状态,建立铁磁材料中的磁化状态及磁偶极子模型中的关荷密度与外磁化场强度、铁磁材料的内禀磁性质以及铁磁材料中磁路和缺陷几何尺寸的关系。 相似文献